The present invention relates to magnetic devices. More particularly, the present invention relates to a magnetic device that employs a current-carrying conductor to provide a magnetic field that assists a write field.
As magnetic recording storage densities continue to progress in an effort to increase the storage capacity of magnetic storage devices, magnetic transition (i.e., bit) dimensions and critical features of the recording device are being pushed below 100 nm. In some cases, the critical dimensions of the write element are decreasing faster than the spacing between the write element and the magnetic medium. This presents a significant challenge in that not only is the magnetic field strength effectively reduced, but the magnetic field profile at the medium is more poorly confined. The result is that off-track fields can cause undesirable effects such as adjacent track or side track erasure. Thus, an important design consideration is to confine the magnetic fields more effectively without significantly degrading the field strength at the medium.
In addition, making the recording medium stable at higher areal densities requires magnetically harder (i.e., high coercivity) storage medium materials. A magnetically harder medium may be written to by increasing the saturation magnetization value of the magnetic material of the recording device to increase the magnetic field applied to the magnetic medium. However, the rate of increase of the saturation magnetization value is not sufficient to sustain the annual growth rate of bit areal densities. Another approach is to provide a stronger write field by incorporating a device adjacent to the tip of the write pole that produces a magnetic field to reduce the coercivity of the magnetic medium near the write pole. This allows data to be written to the high coercivity medium with a lower magnetic field from the write pole. However, many current designs of such write assist devices consume high levels of power to generate the assist field, and the frequency of the assist field produced by these write assist devices is not easily controlled.